Target studies for surface muon production

Abstract

Meson factories are powerful drivers of diverse physics programmes. With beam powers already in the MW-regime attention has to be turned to target and beam line design to further significantly increase surface muon rates available for experiments.For this reason we have explored the possibility of using a neutron spallation target as a source of surface muons by performing detailed Geant4 simulations with pion production cross sections based on a parametrization of existing data. While the spallation target outperforms standard targets in the backward direction by more than a factor 7 it is not more efficient than standard targets viewed under 90 • .Not surprisingly, the geometry of the target plays a large role in the generation of surface muons. Through careful optimization, a gain in surface muon rate of between 30 -60% over the standard "box-like" target used at the Paul Scherrer Institute could be achieved by employing a rotated slab target. An additional 10% gain could also be possible by utilizing novel target materials such as, e.g., boron carbide.

Slow Muons and Muonium

“…Studies for HiMB already benefit conventional meson target designs. 21 HiMB will provide 10 10 µ + /s below 30 MeV/c to the phase-2 Mu3e experiment. The beamline will open up new possibilites for statistically limited muon experiments in general.…”

Prospects for a Muon Spin Resonance Facility in the MuCool Test Area

“…For comparison, TRIUMF accelerates ~10 15 p/s to 500 MeV, typically runs at 100-120 µA [6], and delivers, on average, ~1.5x10 22 POT/year to a muon production target. The PSI cyclotron operates at 590 MeV with a proton current of 2200 A [7], thus potentially delivering a maximum of 4x10 23 POT per year on two graphite production targets. ISIS produces the only pulsed SR beam, delivering 2.5x10 13 protons at 50 Hz onto a graphite target [8].…”

“…The target material and design, especially in terms of target cooling must be considered simultaneously. At PSI a 1 Hz graphite target wheel with radiative cooling is used [7] but at ISIS active edge cooling is used [8]. Required thermal and mechanical properties are discussed followed by a discussion of pion production and Z dependence.…”

Charged lepton flavour violation searches at the Paul Scherrer Institut: Status of the MEGII and Mu3e experiments

“…Muonic rare channels such as the µ + → e + γ decay, the µ + → e + e + e − decay and µ − N → e − N conversion in nuclei are the most promising and complementary cLFV processes (often referred to as "golden muonic channels" [1,[16][17][18][19][20]): (a) The tremendous muon beam intensities (already available: up to few ×10 8 µ/s (continuous, DC) [21,22], available soon: O(10 11 ) µ/s (pulsed) [23,24] and understudy: O(10 10 ) µ/s (DC) [25,26]), implying for huge statistical samples, together with ultimate performing detectors allow for astonishing muonic cLFV SES; (b) The combined phenomenological analysis of these three processes allows for discriminating the underlying operators generating a potential signal, given different process sensitivities to the different operators. Figure 2 shows the history of cLFV experiments based on the golden muonic channels.…”